1. Field of the Invention
The present invention relates to a recording/reproducing system and a recording/reproducing process for adding additional information to information signals, such as image signals, and recording the resultant signals on a recording medium, and for, in reproduction, picking up the additional information added to the information signals and then performing control for reproduction; and a recording device and a reproducing device for use in the aforementioned system and process.
2. Description of Related Art
Recently, there have been provided many reproducing devices such as a digital VTR and a reproducing device for a DVD (Digital Video Disc), and softwares which can be reproduced by use of these devices. Digitized image signals and sound signals have been easily reproduced at home so that images with good image quality can be watched and sounds with good sound quality can be listened to.
Furthermore, there have been also provided abundant image signals and sound signals, or programs through Internet and recording media such as a CD-ROM (Compact Disc ROM), and the digitized softwares provided through Internet and the recording media such as a CD-ROM have been widely used in a personal computer or the like.
However, it is feared that the softwares such as digital image signals provided abundantly in such a manner as above are copied without any restriction. Hitherto, therefore, various copy preventing methods have been adopted to prevent illegal copying of information signals such as image signals and sound signals.
As one of the copy preventing methods, there is known a copy limiting system over plural generations called CGMS (copy generation management system). In this system, 3-stage classified copy control information, i.e., information that copying is free, that copying is allowable for the first generation, or that any copying is prohibited is embedded on an information signal. For example, in the case wherein copying is free, wherein copying is allowable for the first generation, or wherein any copying is prohibited, 2-bit copy control information of “00”. “10” or “11” is embedded in the information signal, respectively. However, in the case wherein any copying is prohibited, the copy control information is not embedded in the information signal.
When the information signal is copied on a recording medium, the copy control information embedded in the information signal according to the CDMS is detected, and then the copy control is performed in accordance with the detected copy control information. In this case, if any copy controlling signal is not detected, the information signal cannot be copied. This is because in the case wherein any copying is prohibited, any copy control information is not embedded.
As described above, control can be performed not only for copying-prohibition or copying-allowance, but also for copying-allowance only for the first generation. Thus, flexible copy preventing control has been able to be performed.
In the case wherein copy preventing control is performed according to the CGMS, however, suppliers of information signals have a desire that copying of the information signals is limited to copying by an individual, for example, at home, i.e., copying for private use even if the copy controlling information that copying is free or that copying is allowable for the first generation is added to the information signal.
In other words, there are no problems in the case wherein an individual copies the information signal on a recording medium at home and then the individual uses the copied information signal; however, it is not preferred for the suppliers of information signals that even information signals the copying of which is allowable are copied many times so that the copied information signals will spread widely to the public.
In order to prevent such spread of copied information signals, it is considered that the suppliers of information signals, in supplying the signals, more frequently add the copy control information that any copying is prohibited to the information signals for supply, or that the cost for supplying information signals becomes expensive. This case is not preferable since copying for private use is also limited.